PCB manufacturers face a dilemma: what’s the most effective way to prevent pollution with heavy metals and other toxic substances for disposable products? The answer is the Restriction of Hazardous Substances (RoHS) standards, a European Union directive that addresses reducing the toxicity of electronics. For a circuit board to meet these requirements, specific materials and chemistry that are compliant with RoHS manufacturing regulations are necessary during fabrication and assembly. These ingredients must be free from contaminants or dangerous compounds above acceptable limits for environmental safety and to prevent fines, recalls, lost sales, and brand damage.
RoHS Manufacturing Protects Environments, People
RoHS regulations restrict using hazardous and toxic materials in electronic products sold or distributed in the European Union. Additionally, the RoHS directive serves as a general framework in regions outside the EU. As materials used in the production of circuit boards can include hazardous substances, the RoHS regulations specify the acceptable limit of these materials at 1000 parts per million (ppm) by weight. Products exceeding these thresholds are not appropriate for sale in the EU.
List of RoHS Materials (maximum permitted concentration 0.1%) |
|
|---|---|
| Lead (Pb) | A component of tin-lead solders, especially eutectic tin-lead, for low melting point and excellent reliability. |
| Mercury (Hg) | A heavy metal providing conductivity in some electronic meters and gauges. |
| Cadmium (Cd) | Batteries (largely superseded by lithium-ion) and steel electroplating. *Note: cadmium has a 0.01% maximum concentration.* |
| Hexavalent chromium (Cr6+) | Some common uses include dyes, paints, inks, plastics, and anticorrosion (including electroplating). |
| Polybrominated biphenyls (PBB), Polybrominated diphenyl ether (PBDE) | Flame retardants. |
| Bis(2-ethylhexyl phthalate (DEHP) | Dielectric fluid in capacitors. |
| Butyl benzyl phthalate (BBP), Dibutyl phthalate (DBP), Diisobutyl phthalate (DIBP) | Plasticizers. |
The foremost casualty of the RoHS standards is eutectic tin-lead solder, a staple of the PCB assembly process. In this step, leaded solders (most often eutectic tin-lead) leveraged the stability and relatively low temperature of tin-lead alloys. However, to limit the environmental accumulation of lead (a toxic heavy metal that can be lethal in small amounts), RoHS outlawed its usage, creating new challenges for manufacturers and long-term electronics reliability.
By specifying the maximum amount of these substances allowed in the manufacturing of PCBs, the RoHS regulations help protect consumers from hazardous materials in a range of products and industries. Maintaining compliance is critical; a partner CM can address these requirements with a comprehensive approach to vetting the relevant aspects of production.
Critical Principles of RoHS-Compliant Manufacturing of PCBAs
RoHS impacts the entire scope of manufacturing as the unintentional inclusion or byproduct of non-RoHS-compliant materials can result in costly rectification. Most, if not all, of the steps of the PCB manufacturing process require some modification to comply with RoHS requirements.
However, three key concepts form the bedrock of RoHS-compliant PCB manufacturing:
- Materials: The most basic requirement for manufacturing a RoHS-compliant PCB is using compliant materials. For example, since RoHS restricted the use of lead in solder, it spurred the adoption of new materials with excellent thermal properties to satisfy the need for lead-free solder. All of the materials and chemicals used by a CM in the assembly of your board must be RoHS compliant.
- Processes: Contaminating RoHS chemistry and materials with non-RoHS substances will impede compliance. Processes must be in place to prevent the inclusion of offending materials above acceptable limits—documented procedures to identify and isolate RoHS-compliant products from non-compliant ones throughout the production process.
- Documentation: All materials used for a PCB must be traceable to meet regulatory requirements. Documentation during manufacturing is crucial to establish records that all materials are RoHS compliant and have not been liable to cross-contamination with non-compliant materials.
Quality CMs ensure PCB manufacturing has these principles at the forefront; those who understand the importance of these regulations will have the experience and procedures to maintain compliance. Larger CMs with volume-driven processes may be unable to guarantee these requirements.
Best Practices for RoHS Manufacturers and Their Partners
The first thing to look for when choosing a contract manufacturer that is RoHS compliant is to make sure they understand and have patterned their processes after the RoHS regulations:
- Can source parts and materials from vendors that are totally RoHS compliant.
- Work with fabrication shops that also comply with RoHS standards.
- Store and process RoHS and non-RoHS chemistry and materials separately.
- Document RoHS requirements during quoting and product review.
- Employ process engineers to monitor production and meet requirements.
At VSE, we understand the importance of the RoHS manufacturing regulations by working with compliant vendors to ensure that all parts and materials used will pass the RoHS requirements. Since 2006, we have utilized a documented procedure to tightly control the identification and compartmentalization of compliant and non-compliant materials. We know that cross-contamination is a big concern, and we have painstakingly defined and crafted our manufacturing processes to guarantee that all RoHS materials are within acceptable limits. Additionally, we provide RoHS conversion design services on legacy products to make revisions compliant.
